The invention that is the subject of this application relates to cigarettes and similar smoking articles.
In United Kingdom Patent Specification No. 2 175 789A there is a disclosure to the effect that cigarettes having a circumference within a range of 10 mm to 19 mm and a free burn rate of the cigarette rod of 25 to 50 mg min.sup.-1 exhibit lower smoke component sidestream deliveries than do comparable conventional cigarettes.
There are disclosed in United Kingdom Patent Specification No. 2 094 130A cigarettes comprising cigarette papers having air permeabilities due to viscous flow of not more than 3 Coresta Units and Do/t ratios in a range of 0.08 to 0.65 cm sec.sup.-1, where Do signifies the coefficient of diffusion of oxygen through nitrogen in the paper and T signifies the thickness of the cigarette paper. Such cigarettes exhibit low deliveries of total particulate matter and nicotine in the sidestream smoke.
A further approach to the obtainment of low component deliveries in the sidestream smoke of cigarettes is by way of using cigarette papers comprising one or more sidestream reducing compounds. Thus, for example, there is a teaching in United Kingdom Patent Specification No. 2 139 869A that the total particulate matter in the sidestream smoke emanating from the lit end of a cigarette during the smoking thereof can be reduced by at least 30% if the cigarette paper comprises one or more, preferably a plurality, of compounds of the group consisting of lithium hydroxide, aluminum hydroxide, calcium hydroxide, potassium formate, sodium formate and sodium acetate.
Another example of the use of sidestream reducing compounds is disclosed in U.S. Pat. No. 4,231,377, which includes sidestream reducing compounds having at least 15% by weight of magnesium oxide or magnesium hydroxide with at least 0.5% of an adjuvant salt selected from the group consisting of the alkali metal salts of acetic, carbonic, citric, nitric, and tartaric acid incorporated in combination in cigarette paper.
It is an object of the subject invention to provide an improved low sidestream cigarette or similar smoking article.
The subject invention provides a smoking article comprising a smoking material rod, which rod comprises smoking material and a wrapper circumscribing said smoking material, said rod not exceeding 20 mm in circumference and said wrapper being of a material comprising a sidestream reducing compound, said material being such that when providing a wrapper of a smoking material rod of conventional cigarette circumference there is effected a reduction of at least 30% in the particulate matter, on a water and nicotine free basis, of sidestream smoke compared with a control rod of the same conventional cigarette circumference and comprising conventional cigarette paper.
The sidestream reducing compound is effective to reduce visible sidestream smoke components without effecting a marked, if any, reduction in gas phase components of sidestream smoke. These compounds can be broadly summarized as Group I and Group IIA metal salts of organic and inorganic acids, wherein the organic acids include acetic, carbonic, oxalic, formic, benzoic, citric, lactic, and tartrate and the inorganic acids include nitric, ferric, boric, hydroboric, and hydroiodic. Among the compounds which can be used, singly or in combination, as sidestream reducing compounds are alumina, aluminum hydroxide, barium acetate, barium bromide, barium nitrate, calcium hydroxide, caesium acetate, caesium carbonate, caesium nitrate, lithium hydroxide, lithium oxalate, magnesium hydroxide, magnesium iodide, magnesium oxide, potassium acetate, potassium benzoate, potassium bicarbonate, potassium citrate, potassium formate, potassium lactate, potassium nitrite, potassium oxalate, potassium oxaloferrate (III), potassium tartrate, potassium tetraborate, rubidium acetate, rubidium carbonate, rubidium hydroxide, rubidium nitrate, sodium acetate, sodium nitrate, sodium oxalate, and Attapulgite clay. Some of the compounds which can be used as sidestream reducing compounds are disclosed in U.S. Pat. No. 4,461,311 and include the sodium and potassium salts of acids such as carbonic, citric, tartaric, fumaric, oxalic, malonic, succinic, nitric, and phosphoric acid.
Several other United Kingdom patents disclose compounds which may utilized as sidestream smoke reducing compounds. For instance, United Kingdom Patent Specification No. 2119417B teaches the use of a grade of magnesium oxide which is unreactive with water with magnesium hydroxide having an average particle size of less than 10 micrometers which may be utilized as a sidestream reducing compounds. Another United Kingdom Patent, Specification No. 2118986B, teaches the use of magnesium oxide and an amorphous magnesium hydroxide gel, and the use of magnesium oxide and an amorphous magnesium hydroxide gel in combination with an adjuvant salt to provide a sidestream reducing compound. In addition, United Kingdom Patent Specification No. 2118986B discloses the use of sidestream reducing compounds having a superficial surface area of at least eighty square meters containing up to about 15% by weight of at least one alkali metal salt selected from sodium and/or potassium salts of carbonic acid, formic acid, acetic acid, propionic acid, malic acid, lactic acid, glycolic acid, citric acid, tartaric acid, fumaric acid, oxalic acid, malonic acid, nitric acid, phosphoric acid, sodium citrate and potassium citrate. other sidestream reducing compounds included are water insoluble clays, and/or oxides, peroxides, carbonates, phosphates, sulfates, aluminates and silicates.
Suitably, the material of wrappers of smoking articles according to the present invention is paper. Water insoluble sidestream reducing compounds may be added in powder form as a filler to the paper furnish during the making process of paper wrapper material. Water soluble sidestream reducing compounds are preferably applied to the wrapper material in aqueous solution.
The smoking material of smoking articles according to the subject invention preferably comprises or consists of cut tobacco, a proportion of which tobacco may be expanded tobacco. The smoking material may comprise reconstituted tobacco or tobacco substitute material.
The length of the smoking material rod is advantageously at least 60 mm and the rod should preferably yield not less than six puffs, and more preferably not less than seven puffs when smoked under standard machine smoking conditions. The rod is preferably of uniform cross-sectional shape and dimensions throughout the length of the rod. If the rod is of circular cross-section, the circumference of the rod may be as low as 10 mm for example, but is preferably not less than 12.5 mm.
Advantageously, the circumference of the smoking material rod does not exceed about 19 mm and more advantageously it may be less than 18 mm.
Preferably, cigarettes according to the subject invention comprise filter or mouthpiece means attached to the smoking material rod at one end thereof.
Preferably, wrappers of smoking articles according to the present invention are of a low permeability, the permeability thereof being, for example, not more than 20 Coresta Units, and more preferably not more than 12 Coresta Units.
In order to further the understanding of the present invention, examples according thereto will now be described.